In application Serial No. 820,410 there is disclosed a slot machine type amusement apparatus having means for randomly advancing one or more drums bearing symbols, a fraction of a turn, before a playing cycle, so as to cause to be displayed a different combination of symbols, thereby to accord the player an opportunity to win a prize. In a modified embodiment of this concept it is desired that the player have the opportunity to selectively effect rotation of one or more of the drums, each equivalent to only one index position, so that the next in line symbol on a drum is moved into registration with the viewing area of the apparatus. Thus, depending upon the combination of symbols resulting from the previous playing cycle, the player, upon initiating a new playing cycle may selectively effect rotation of one or more of the drums equivalent to one index position for each drum so as to attempt to obtain a winning combination of symbols in the viewing area. It has been found in actual practice that with the use of conventional mechanism it is difficult, if not impossible, to control the operation of the apparatus so that the advance of the drum is limited to only one index position. Accordingly, instead of advancing only a single index position the drum frequently may advance more than one index position which defeats the desired sequence of operations of the apparatus.